U.S. patent number 4,268,115 [Application Number 06/044,575] was granted by the patent office on 1981-05-19 for quick-release fiber-optic connector.
This patent grant is currently assigned to Tetra-Tech, Inc.. Invention is credited to Steven W. Braun, Charles S. Slemon.
United States Patent |
4,268,115 |
Slemon , et al. |
May 19, 1981 |
Quick-release fiber-optic connector
Abstract
A metal ferrule is attached to the end of an optic fiber, with
the ferrule end and fiber tip coplanar. The ferrule and fiber are
slidably mounted in a housing which incorporates a quick-release
connecting catch, and are abutted by spring-loading against a
mating optical device. The catch is adapted to engage a fitting
secured to the mating optical device.
Inventors: |
Slemon; Charles S. (Encinitas,
CA), Braun; Steven W. (Encinitas, CA) |
Assignee: |
Tetra-Tech, Inc. (Pasadena,
CA)
|
Family
ID: |
21933124 |
Appl.
No.: |
06/044,575 |
Filed: |
June 1, 1979 |
Current U.S.
Class: |
385/88;
385/92 |
Current CPC
Class: |
G02B
6/3825 (20130101); G02B 6/3834 (20130101); G02B
6/4292 (20130101); G02B 6/3893 (20130101); G02B
6/3869 (20130101) |
Current International
Class: |
G02B
6/42 (20060101); G02B 6/38 (20060101); G02B
005/14 () |
Field of
Search: |
;350/96.20,96.21,96.22 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Levy; Stewart J.
Attorney, Agent or Firm: Lippman; Peter I.
Claims
We claim:
1. A connector, for use in presenting the tip of a sheathed optic
fiber to a mating optical device for light transmission between
such tip and such device, the connector comprising:
a fitting adapted to be affixed to such mating optical device;
a ferrule, adapted to be affixed to the end of such optic fiber,
the ferrule defining:
a cavity which penetrates completely through the ferrule and is
adapted to accept such fiber, whereby the tip of such fiber may be
exposed flush with one end of the ferrule; and
a first spring anchor;
a connector body guiding the ferrule and having a quick-release
connecting catch that is adapted to engage the fitting, whereby the
connector body may be held in fixed relation to such mating optical
device, the said catch comprising:
a hook which is carried by the connector body, formed to engage the
fitting, and spring-loaded toward engagement with the fitting;
and
manipulable means for retracting the hook, against the
spring-loading, to disengage the hook from the fitting; the
manipulable hook-retracting means comprising a housing which at
least partly covers the connector body and is slidably mounted
thereto, and which defines an aperture through which the hook
extends;
the connector body being slit in such relation to the hook as to
form a spring which urges the hook outward through such aperture
and toward engagement with the fitting; and
the hook being shaped for retraction into the housing in response
to sliding manipulation of the housing;
a second spring anchor secured to the connector body; and
spring means engaging the two anchors and adapted to urge the said
one end of the ferrule toward such mating optical device.
2. The connector of claim 1 wherein the outer surface of the
ferrule along part of its length is relieved to accommodate inward
motion of the slit spring portion of the body when the hook is
retracted by manipulation of the housing.
3. The connector of claim 1 wherein:
the connector body is slit in a plurality of locations to form a
plurality of springs each having a said hook thereon; and
the housing has a plurality of said apertures, through one of
which, respectively, each said hook extends and is outwardly urged
by said respective spring.
4. The connector of claim 3, wherein the outer surface of the
ferrule along part of its length is relieved to accommodate inward
motion of the slit spring portions of the body when the hooks are
retracted by manipulation of the housing.
5. A connector, for use in presenting the tip of an optic fiber to
a mating optical device for light transmission between such tip and
such device, the connector comprising:
a ferrule, adapted to be affixed to the end of such optic fiber,
the ferrule defining:
a cavity which penetrates completely through the ferrule and has
permanently affixed within it a section of miniature steel tubing
adapted to hold such optic fiber, whereby the tip of such fiber may
be exposed flush with one end of the ferrule; and
a first spring anchor;
a connector body guiding the ferrule and comprising a quick-release
connecting catch;
a fitting adapted to be affixed to such mating optical device and
adapted to engage the catch, whereby the connector body may be held
in fixed relation to such device;
a second spring anchor secured to the connector body; and
spring means engaging the two anchors and adapted to urge the said
one end of the ferrule toward such mating optical device.
6. A connector, for use in presenting the tip of a sheathed optic
fiber to a mating optical device for light transmission between
such tip and such device, the connector comprising:
a ferrule, adapted to be affixed to the end of such optic fiber,
the ferrule defining:
a cavity which penetrates completely through the ferrule and is
adapted to accept such fiber, whereby the tip of such fiber may be
exposed flush with one end of the ferrule; and
a first spring anchor;
a connector body guiding the ferrule and comprising a quick-release
connecting catch;
a fitting adapted to be affixed to such mating optical device and
adapted to engage the catch, whereby the connector body may be held
in fixed relation to such device;
a second spring anchor secured to the connector body; and
spring means engaging the two anchors and adapted to urge the said
one end of the ferrule toward and into positive abutment with such
mating optical device when the fitting is affixed to such device
and is engaging the connector-body catch; and wherein:
the ferrule has a longitudinal axis, and defines an outer guide
surface parallel to that axis; and
the fitting defines a guide cavity adapted to accept and slidably
engage the outer guide surface without longitudinally restraining
the ferrule; and
when the fitting is affixed to such device and is engaging the
connector-body catch, the connector body does not longitudinally
restrain the ferrule.
7. The connector of claim 6, wherein the catch comprises:
a hook which is carried by the connector body, formed to engage the
fitting, and spring-loaded toward engagement with the fitting;
and
means manipulable to retract the hook, against the spring-loading,
to disengage the hook from the fitting.
8. A connector, for use in presenting the tip of a sheathed optic
fiber to a mating optical device for light transmission between
such tip and such device, the connector comprising:
a ferrule, adapted to be affixed to the end of such optic fiber,
the ferrule having a longitudinal axis and defining:
a cavity which penetrates completely through the ferrule and is
adapted to accept such fiber, whereby the tip of such fiber may be
exposed flush with one end of the ferrule;
a first spring anchor; and
an outer guide surface parallel to the ferrule longitudinal
axis;
a connector body guiding the ferrule and comprising a quick-release
connecting catch;
a fitting adapted:
to be affixed to such mating optical device;
to engage the catch, whereby the connector body may be held in
fixed relation to such device; and
to accept and slidably engage the outer guide surface of the
ferrule, without longitudinally restraining the ferrule;
a second spring anchor on the connector body; and
spring means engaging the two anchors and adapted to urge the said
one end of the ferrule toward such mating optical device when the
fitting is affixed to such device and is engaging the
connector-body catch; and
said connector body does not longitudinally restrain the ferrule
when the fitting is affixed to such mating device and is engaging
the catch.
9. The connector of claim 8, wherein the catch comprises:
a hook which is carried by the connector body, formed to engage the
fitting, and spring-loaded toward engagement with the fitting;
and
manipulable means for retracting the hook, against the
spring-loading, to disengage the hook from the fitting.
Description
BACKGROUND OF THE INVENTION
1. General Field
Our invention is in the field of fiber optics; and in particular
relates to disconnectable connectors for optically coupling optical
fibers to each other, or to light sources or detectors.
2. Prior Art
The conventional arrangement for coupling optic-fiber components to
each other is illustrated as FIG. 2. A fiber 111 is cemented into a
metal ferrule 112, and the cable sheathing 119 terminated in an
enlarged portion of the central cavity of ferrule 112 or in any
other convenient fashion. Held securely to ferrule 112, as by
flange 113 and circlip 114, is connector shell 115, with internal
threads 117.
These threads mate with external threads 123 of another fitting 122
that is attached to mating optical device 121--which may contain
another fiber, or may be a source or detector. Of course when the
threads are screwed together the outer diameter of ferrule 112
slides within the inner diameter of fitting 122. Precision
machining is required at surfaces 116, 118, 126, 125, 124 and 112,
to assure a smooth sliding fit, concentricity of the fiber-optic
tip and the end of a mating fiber in device 121 (or in any case the
end of cavity 124), and proper abutment of the fiber-optic tip 118
with the transmissive surface 127 of mating optical device 121. In
particular, exceedingly careful control of the longitudinal
distance between surfaces 116 and 118, and that between surfaces
126 and 125, is required to obtain reliably an actual contact
between optic fiber 111 and mating surface 127, without excess
pressure that could cause breakage or scratching if the connector
shell 115 is screwed on too far.
While serving a useful purpose, such connectors have certain
limitations. They require considerable time for connection and
disconnection; and equipment design must leave ample "finger room"
all around each connector for screwing and unscrewing--tending
toward unduly bulky apparatus. The precision machining requirements
also make these connectors relatively expensive.
Connectors offering quick-connect and quick-disconnect capabilities
are common in another field--that of electronics. In that field
such connectors have resolved the annoyances of time and equipment
bulk analogous to those mentioned above for fiber-optic equipment,
by providing push-pull connectors easily and quickly inserted and
withdrawn with fingers placed on only two sides of the connector,
without rotation. For example, a brochure published in August 1977
by Lemo U.S.A. Inc. of Berkeley, California illustrates a line of
quick-connect/disconnect electrical couplings accommodating coaxial
cable and multiconductor cables having up to 18 wires.
Another publication, one-page and undated, from the same company
summarizes the same information as in the August 1977 brochure, and
also mentions four other product lines: "high voltage connectors,"
"fiber optic connectors," "fluidic connectors," and "cable
assemblies." None of these latter four product lines is illustrated
or detailed, and actual inquiry with the firm reveals that it does
not have "fiber optic connectors" available. If that firm did have
such connectors they might well be of a screw type such as
appearing in FIG. 2.
There are problems associated with fiber-optic connectors which do
not arise in regard to electrical or electronic connectors, and to
our knowledge no prior-art disclosure provides solutions to the
particular problems of quick-release fiber-optic connectors. In the
case of electrical connectors, such as those of Lemo U.S.A. Inc.,
the male pins on one half of the connector simply slide into the
female pins on the other half of the connector, to whatever depth
results from the positioning of the connector shell (whether
quick-connect or not). There is no need to control the insertion
depth accurately. But depth control is essential for fiber
optics.
SUMMARY OF THE INVENTION
Our invention makes use of a quick-release connector shell
configuration which is conventional in electronics, and surrounding
the optic fiber a hollow-centered ferrule which is in its general
outlines conventional in fiber optics. However, in the interfacing
between these two components we have introduced innovations which
eliminate some of the precision machining required in prior
fiber-optic devices.
By solving this interfacing problem we also make possible use of
push-pull attachment and release motions, thereby eliminating the
excess "finger room" required for connectors that are attached and
released.
In particular a spring stop is provided on the ferrule, and the
ferrule is left floating with respect to the connector shell (which
in our invention incorporates quick-release features). A spring is
mounted in compression between the spring stop on the ferrule and
the "back" end of the connector shell (that is, the end furthest
from the mating optic component). The spring pushes the ferrule,
and with it the optic fiber, forward toward the mating optical
device.
It is still necessary to precision-face the ferrule, and to
precision-match the diameters of the ferrule and its mating guide
cavity, but depth adjustment is provided by the spring loading, and
extra "finger room" is unnecessary because of the push-pull type of
connector shell employed.
The principles and features introduced above, and their advantages,
may be more-fully understood from the detailed disclosure
hereunder, with reference to the accompanying drawings, of
which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of one connector embodying our
invention, except that the optic fiber and its sheath are not shown
in cross-section. Both the male and female sections of the
connector are illustrated, as used in connecting an optical fiber
to a light source or detector.
FIG. 2, already discussed, is a similar view, in cross-section
except for the fiber and sheath, of a typical prior-art
connector.
FIG. 3 is an external view, taken at right angles to the view of
FIG. 1, showing one component used in the connector of FIG. 1.
FIG. 4 is a cross-sectional view of another embodiment of the
female section of the connector shown in FIG. 1, this one for use
in coupling together two optical fibers which are both terminated
in quick-release male connector sections. The male connector half
is not shown in cross-section.
FIG. 5 is a cross-sectional view of a third embodiment of the
female section of the connector shown in FIG. 1, but this one is
for use in coupling two optical fibers when only one of the two is
terminated in a quick-release male connector section. The latter is
not shown in cross-section.
DESCRIPTION OF PREFERRED EMBODIMENTS
As shown in FIG. 1 our invention makes use of a hollow, generally
cylindrical ferrule 12 permanently affixed as by epoxy cement to
the end of an optic fiber 11. The forward end of the fiber 11
extends and fits closely within a small-diameter hole 72 in the
ferrule 12, so that the fiber's polished flat tip 39 is
substantially coplanar with the end face 18 of the ferrule 12. This
forward end of the fiber is not otherwise sheathed, the sheath 19
extending only within the slightly larger-diameter hole 71 at the
other end of the ferrule 12.
The outer surface of the ferrule 12 is relieved at 73, for a
purpose to be explained below, and comprises a cylindrical flange
16 which acts as a first spring stop for generally helical spring
17. The end face 18 is precision machined to be both flat and
perpendicular to the ferrule axis.
The ferrule 12 is slidably retained in a structure formed by
threading a retainer 13 into a connector body 14, which is
generally cylindrical though it incorporates a tapered portion 74
and outward-protruding hooks 31. Part of the body 14 is slit as
along three sides 33 (see FIG. 3) of a rectangular pattern, forming
a tongue (or cardan spring) extending from the root 34 to the hook
31. This pattern is repeated in the area of the other, diametrical
hook.
Ferrule 12 slidably protrudes from body 14 but is restrained from
sliding completely out of the body 14 in the forward direction by
engagement of the flange 16 with the tapered portion 74 of the body
14. Restraint in the opposite direction is provided by the end wall
75 of retainer 13, which is threaded at 77 to the body 14. The end
wall 75 defines an aperture 76 only large enough to pass the fiber
casing 19, not the ferrule 12.
The retainer 13 acts as a second spring stop for the spring 17, so
the spring 17 urges the ferrule 12 forward (that is, to the right
as drawn).
Closely but slidably encircling the body 14 is an outer housing 15
which is generally cylindrical though it has a tapered portion 78.
This tapered portion 78 by engaging the corresponding tapered
portion 74 of the body 14 prevents the housing 15 from sliding
rearward completely off the body 14. Formed in the smaller-diameter
portion of the housing 15 are apertures 32 through which extend the
hooks 31.
The hooks 31 prevent the housing 15 from sliding forward completely
off the body 14, but their primary purpose is to engage a mating
annular groove 23 in the interior cylindrical surface 24 of the
female connector section 22. The engaging of hooks 31 with groove
23 is what secures the female connector section 22 to the male
section 10 comprising ferrule 12, spring 17, body 14, retainer 13
and housing 15.
Because of the ratchet-tooth shape of the hooks 31, when the male
section of the connector is inserted into the female section 22 the
inner surface 24 engages the inclined surface of each hook 31,
pushing the hooks 31 inward toward the ferrule 12, against the
spring action of cardan section 34. The relieved portion 73 of the
outer surface of the ferrule 12 accommodates the inward motion of
the hooks 31.
Meanwhile the conical portion 26 of the female connector 22 helps
to guide the forward end of ferrule 12 into the precision-diameter
inner cavity 27, which forces the finished faces 18 and 39 to be
accurately parallel with the mating surface 25 of the light source
or detector 21.
With continuing insertion the hooks 31 reach the groove 23, and
they spring radially out into the groove.
Meanwhile the spring 17 urges the finished faces 18 and 39 of the
fiber 11 and ferrule 12, respectively, forward into abutment with
the mating surface 25 of the light source or detector 21. Spring 17
then tends to urge the body 14 outward, seating the hooks 31
against the groove 23 while holding the fiber face 18 with a
controlled amount of force against the mating surface 25.
Rearward tension on the fiber sheath 19 does not retract the hooks
31 from the groove 23, and the connector sections remain locked
together.
Rearward manipulation of the housing 15, however, forces the edges
of the apertures 32 against the inclined surfaces of the hooks,
retracting the hooks. Spring 17 helps start the body 14 and housing
15 out of the female section 22, and the connector sections readily
separate.
The various components of the male connector section, as already
noted, are composed of generally cylindrical and conical
subsections, with the exception of the spring 17, threads 77, hooks
31 and slits 33.
The female section has cylindrical outer surfaces 82 and 84,
conical outer surfaces 81 and 83, and as convenient hexagonal outer
surface 85. Cylindrical recess 86 with flat circular end wall 87
accommodates a standard transistor housing can, such as a type
known as "TO-5." Light emitters and detectors are available in such
cans. For applications where desired, the female section 22 may
have incorporated in it mounting features, such as an external
thread, to facilitate attachment to a panel or the like.
FIG. 4 illustrates a coupling used for interconnection of two optic
fibers terminated respectively in two male connector sections 10,
10a made as in FIG. 1. This coupling is essentially two of the
female section 22, back-to-back, but without the recess 86.
Cylindrical surfaces 44 and 47, grooves 43, and conical surfaces 46
are dimensioned identically with, and have the same functions as,
the corresponding surfaces 24, 27, 23 and 26 of FIG. 1.
FIG. 5 illustrates a female connector section 52 used for
interconnection of two optic fibers only one of which terminates in
a quick-release male connector section 10 of the type in FIG. 1,
the other fiber 61 carrying a less-expensive ferrule 62. The latter
fiber 61 is permanently affixed as by epoxy cement within the
narrow-diameter hole 94 of the ferrule 62 so that the finished face
69 of the fiber 61 is coplanar with the flat end 95 of the ferrule
62. Outer surfaces 67 and 64 are cylindrical, section 63 conical,
and 65 flat. Inner surface 93 accepts the end of sheath 68.
Connector section 52, like section 22 of FIG. 1, may be provided
with mounting features.
The outer surface 67 is accurately machined to the same diameter as
the forward end of the other ferrule 12 (FIG. 1), and the face 95,
like the face 18 of the other ferrule 12, is precision-machined to
be both flat and perpendicular to the ferrule axis.
The small-diameter portion 67 of the ferrule 62 is inserted into
the female connector section 52 from the plain end, so that the
surfaces 65 and 59 abut, and is secured by two setscrews 58. The
internal surfaces 54, 53, 56 and 57 of the female connector section
52 have the same dimensions and purposes as the corresponding
surfaces 24, 23, 26 and 27 of the female connector section 22 in
FIG. 1.
In effect the less-expensive ferrule 62 and the female connector
section 52 after being secured together by setscrews 58 form a
unitary component which can be considered permanently affixed to
the optic fiber 61. This unitary component has a blind cylindrical
hole 57 whose bottom or end wall 95 is accurately flat and
perpendicular to the axis of the hole 57, and carries in it the
similarly finished coplanar tip 69 of the fiber 61. In principle
such a unitary component could be made in one piece, and the fiber
cemented into place in it. In practice, however, the difficulties
of machining a precision-flat-bottomed narrow hole, obtaining
coplanar positioning of an optic fiber with the flat bottom, and
cleaning away excess cement at the bottom of such a hole render
unitary construction inferior to the two-part configuration
described.
In manufacture of both ferrules 12 and 62, precision machining of
the small-diameter holes 72 and 93, respectively, can be difficult
and quite expensive. We have found it more expeditious and
economical to employ sections of miniature steel tubing, such as
that used for hypodermic needles, as bushes or intermediates. Such
tubing is available in diameters directly suitable for use with
standard-diameter optic fibers.
It may be noted that in the design of FIG. 1 the spring 17 is
anchored at spring stops consisting of retainer 13 and flange 16,
and spring 17 operates in compression to push the ferrule 12
forward relative to the body 14 and housing 15. Other
configurations accomplishing the same purpose can now readily be
envisioned, including anchors from which a spring acts in tension
to pull the ferrule 12 forward relative to the body 14 and housing
15.
Our invention is not limited to generally coaxial connector
geometries, nor is it limited to designs based on figures of
rotation, or to single-fiber connectors. That is, connectors
lacking cylindrical symmetry, connectors having rectangular,
irregular, or otherwise shaped ferrules and bodies, and even
connectors carrying multiple independent optical fibers are within
the scope of our invention. In such variant designs it is not a
requirement that the housing, whose manipulation retracts the
hooks, actually encircle the connector body; in some such
embodiments the housing could be merely a sliding outer plate.
The foregoing disclosure is intended to be exemplary only, not to
limit the scope of our invention--which scope is to be ascertained
only by reference to the following claims.
* * * * *